Car Gauges 101: What You Need to Know

What’s going on under the hood is important to any driver, but especially for owners of finicky classic cars. So, reliable gauges are critical.

While warning lights usually alert you to a problem, a well-configured set of gauges provides precise details to confirm peak performance or to avoid an issue in advance. With today’s large digital screens, the ability to create custom configurations and cool visual layouts is unprecedented.

The Basics

Old-school three-gauge kit

The first step is to define what information is critical for your specific vehicle. For example, if you are driving a turbocharged vehicle, you probably want to know the boost pressure. For a run down the strip, a prominent tachometer with a shift light is key to understanding when to shift.

Let’s not overlook the essentials. For example, suppose you drive an older car with only warning lights. In that case, adding a basic gauge kit can help you keep track of things like water temperature, oil pressure, and vehicle voltage. These gauges will alert you to a malfunction before it becomes a threat, preventing a costly repair.

Three pod A-pillar gauge mount

Older cars often rely on analog gauges. However, these can be less precise and subject to failure. For example, an analog speedometer might show speed increments in units of five or 10 miles per hour but won’t display an accurate speed. Aftermarket gauges can replace the analog sensor with more detailed digital information.

Most gauge kits are easy to install and come with the necessary sensors and fittings for installation under the dash, on its face, or along the driver’s A-pillar. In addition, these kits come in analog and digital versions in various styles to complement your car’s interior.

Vintage and Restoration Gauges

AutoMeter Sport Comp gauge kit

There is nothing wrong with staying true to a classic look, replacing the gauges with a new set that replicates the original. Plenty of authentic and properly functioning instruments and gauges are available for any vintage restoration project. The volume and range of gauge sets available on eBay are remarkable.

Many are newly manufactured or in new-old-stock (NOS) condition. Prices vary with the condition and design of the gauges, but expect to pay more when a component is period-correct and authentic. A period-correct set of replacement gauges could cost less than $1000, depending on rarity. Some vendors can even squeeze a few more gauges into the original dash.

Resto-Mod Gauges

AutoMeter digital Invision dash kit for 1987-1993 Ford Mustangs

Restoration of a classic vehicle often means using factory-original parts. But you can free yourself up by taking a resto-mod approach, using state-of-the-art modern technology and components to take advantage of technological advances. Since most engines need lots of information to be effective, why not give that information to the driver?

Outside temperature, incline slope, and transmission fluid temperature can be easily displayed. Gauges can employ the latest digital technology but retain a desired vintage style.

Digital technology allows more information to be stored in an instrument panel in an easy-to-read format. For many drivers, that’s more important than being pure. With a button press, a fuel gauge display can show miles per gallon since the last fill-up, instantaneous miles per gallon, or how far you can travel with the current fuel level. The simplest digital gauges can be acquired for less than $400. As the complexity grows, so will the price.

Virtual Gauges/Heads-Up-Displays (HUDs)

Aftermarket heads-up display projected on windshield

One of the newest automotive trends is virtual heads-up display (HUD) gauges connected to your vehicle’s OBDII diagnostic port. These devices pull data directly from the vehicle’s computer system and display desired information on your windshield in your line of sight. Others use a single gauge pod on the dash to display a rotating data set. A HUD lets you focus on the road while gleaning information about vehicle conditions or turn-by-turn navigation instructions.

Heads-up displays offer a range of options.

HUDs can also display rpm, fuel consumption, coolant temperature, mileage, voltage, and even map directions. Connecting these devices can be extremely simple, using Bluetooth technology or a single cable connected to your OBDII port. The array of data is staggering. The simplest displays are less than $100, while more sophisticated units are available for $500 or less.